Esperanto (help·info) is the most widely spoken constructed international auxiliary language Its name derives from Doktoro Esperanto, the pseudonym under which L. L. Zamenhof published the first book detailing Esperanto, the Unua Libro, in 1887. The word esperanto means "one who hopes" in the language itself. The language's original name was "La Internacia Lingvo." Zamenhof's goal was to create an easy to learn and politically neutral language that would serve as a universal second language to foster peace and international understanding. Esperanto has between 100,000 and 2 million speakers in about 115 countries, and approximately one thousand native speakers, i.e. people who learned Esperanto as one of their native languages from their parents. Although no country has adopted the language officially, Esperanto did get official recognition by UNESCO in 1954 Today, Esperanto is employed in world travel, correspondence, cultural exchange, conventions, literature, language instruction, television, movies, and radio broadcasting. The first international Esperanto congress was organized in France, Boulogne-sur-Mer, in 1905. Since then international conferences and meetings have been organized around the world with Esperanto every year. At least one major search engine, Google, offers searching of Esperanto-related websites via an Esperanto portal.

There is evidence that learning Esperanto may provide a good foundation for learning languages in general. Esperanto is also the language of instruction in one university, the Akademio Internacia de la Sciencoj in San Marino.

EsperantoIsland in ZedIslands off LivingstonIsland, Antarctica is named after the constructed international language of Esperanto.